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Branch Management and Atomic Merge in a Continuous Integration Environment Yi Zhang and Ray Chang EMC Corporation © 2011
Branch Management and Atomic Merge in a Continuous Integration Environment Yi Zhang and Ray Chang EMC Corporation
© 2011
AGENDA
THE ISSUES • What’s Wrong? THE SOLUTIONS • The New Branch and Defect Model • The Atomic Merge Tool – Logical Flow • Integration with Defect-Tracking
CONCLUSIONS • Achievements • Remaining Issues
Q @ A
THE ISSUES – What’s wrong with this version tree?
THE ISSUES
• Anarchic Branching • Merge-phobia, unable to merge • Tremendous loss in productivity
Stubborn and egregiously harmful institutional habits formed over the years. Migrating to continuous integration exacerbated the issues.
THE SOLUTIONS – New Branch Model
• The branch model and naming conventions
THE SOLUTIONS – New Defect Model
• The defect model and Perforce directory structure
THE SOLUTIONS – The merge tool
• No significant change in merge habit • Improvement limited on the Defect-tracking side • Divergent branches still an issue
Based on “p4 integrate” of P4PERL, implemented an auto-merge tool to merge daily atomically among branches.
THE SOLUTIONS – The atomic merge tool
• Logical flow chart of the merge tool
THE SOLUTIONS – The atomic merge tool
A few assumptions: • Changelist restricted within a project branch • Merge occurred among the tips • Exclusions override the atomic rule
THE SOLUTIONS – Integration with defect-tracking
THE SOLUTIONS – The atomic merge tool
A few more points: • Web interface for ad hoc merge requests • Integration with the continuous integration tool • Running quality tool as a step of post-merge verification
CONCLUSIONS
Achievements: • A set of branching and merging policies are established and implemented • Atomic merge tool is successfully adopted by many teams and sites • Over 95% of automatic merge rate, significantly reduced manual work and enhanced productivity
CONCLUSIONS
Remaining issues: • How to prevent merge-up? • “p4 integrate” doesn’t always recognize duplicated check-ins. • Significant number of project teams not on board yet.
QUESTIONS @ ANSWERS
